JP2003187746A - Cold cathode fluorescent lamp and lighting unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode fluorescent lamp and a lighting unit which avoid the damage and deterioration of the neighboring members by absorbing/ removing radiated ultraviolet rays. <P>SOLUTION: The cold cathode fluorescent lamp comprises a glass tube 12 on the inner surface of which is formed a fluorescent film and in which are enclosed a rare gas and mercury, a pair of cold electrodes 14a, 14b sealed opposed to each other in ends of the glass tube 12, and lead wires 15a, 15b for electrical supply the ends of which, respectively, are connected to the cold electrodes 14a, 14b and the other ends of which are hermetically sealed and extended to the outside of the glass tube 12, wherein a resin layer 16 containing an ultraviolet absorbent of 1 to 30 μm in thickness is coated along the length of the outer surface of the glass tube 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode fluorescent lamp and an illuminating device, and more particularly to a cold cathode fluorescent lamp and an illuminating device suitable for a light source such as a liquid crystal display, an instrument display panel and a scanner.

[0002]

2. Description of the Related Art In a liquid crystal display such as a personal computer, a word processor and a liquid crystal television, a cold cathode fluorescent lamp, which has a small temperature rise due to lighting operation, is used as a light source for a backlight. That is, as shown in FIG. 4 in a cross-sectional view of a main part configuration, a glass tube 2 having a phosphor film 1 formed on an inner wall surface thereof and a discharge medium sealed therein, and facing both ends of the glass tube 2. A pair of enclosed and arranged discharge electrodes 3a and 3b, and the discharge electrode 3
The cold cathode fluorescent lamp 5 has one end connected to a and 3b and the other end having power supply lead wires 4a and 4b which are hermetically sealed and led out of the glass tube 2.

Here, the glass tube 2 has, for example, an outer diameter of 1.
It is about 2 to 10.0 mm and the length is about 50 to 800 mm. The discharge medium is a mixed system of one or more rare gases such as xenon, argon and neon and mercury. And
This type of cold cathode fluorescent lamp 5 includes a power supply lead wire 4a,
When a required high-frequency voltage (for example, a voltage of 20 to 100 KHz, a voltage of 1 to 2 KV) is applied to the discharge electrodes 3a and 3b via the 4b, discharge is started between the discharge electrodes 3a and 3b, and ultraviolet rays are generated in the glass arc tube 2. Radiates. The ultraviolet light thus radiated is converted into visible light by the phosphor film 1 on the inner wall surface of the glass arc tube 2 and functions as a light source.

[0004]

The cold cathode fluorescent lamp 5 has a feature that it has a long life and the like, but on the other hand, as the performance of the liquid crystal display becomes higher, problems caused by the light source become a problem. . That is, the cold cathode fluorescent lamp emits light having a spectral characteristic as shown in FIG.
It exhibits high radiation intensity in the region of 0 to 620 nm, but emits ultraviolet rays having a wavelength of 400 nm or less. The configuration of the cold cathode fluorescent lamp according to this characteristic example has an outer diameter of the glass tube of 2.
Approximately 221m in overall circle with 6mm and 2.0mm inside diameter
m, the distance between the electrodes is 211 mm, the discharge medium is a mixed rare gas of neon and argon, and mercury.

When the cold cathode fluorescent lamp 5 is used as a light source for a backlight of a liquid crystal display device, this ultraviolet radiation causes a structure made of a peripheral component such as a light guide plate of a backlight unit, especially a synthetic resin. This raises a problem that the member is likely to be damaged or deteriorated, and the durability thereof is deteriorated. 6 (a) and 6 (b) show an example of the main part configuration of the backlight unit. FIG. 6 (a) is a development view,
(B) is a sectional view.

In FIGS. 6A and 6B, 6 is a light guide plate made of, for example, acrylic resin, and 7a and 7b are the light guide plates 6 described above.
Reflectors 5a, 5b, 5c and 5d arranged and mounted on the pair of side wall surfaces facing each other are the reflectors 7a,
It is a cold cathode fluorescent lamp that is mounted and arranged as a pair on the reflecting surface of 7b. Further, 8 is a reflection sheet arranged on the one main surface side of the light guide plate 6, 9a and 9b are light shielding sheets arranged and mounted on the other side wall surfaces of the light guide plate 6, and 10 is the light guide plate 6. Reference numeral 11 denotes a diffusion sheet disposed on the other main surface side, and 11 denotes a lens sheet disposed on the diffusion sheet 10 surface side.

As described above, the backlight unit is
For example, the light guide plate 6 is usually made of acrylic resin in consideration of workability and cost. When the acrylic resin is continuously irradiated with ultraviolet rays, the acrylic resin changes its color to yellow, and as a result, the brightness or the brightness maintenance ratio may be decreased, and the function of the backlight unit may be impaired.

In response to the problem caused by the irradiation of the cold cathode fluorescent lamp 5 with ultraviolet rays, the glass tube 2 is made of glass containing an ultraviolet ray blocking component, or the inner wall surface of the glass tube 2 (phosphor film 1). It is also known that a metal oxide layer (film) that transmits visible light but reflects ultraviolet light is provided between (and between) to reduce or prevent the emission of ultraviolet light.
However, a structure in which a metal oxide layer (film) that transmits visible light but reflects ultraviolet light is provided on the inner wall surface of the glass tube 2,
Alternatively, the configuration in which the glass tube 2 itself has the ultraviolet absorbing property does not sufficiently reflect or block the ultraviolet in any case, and as a result, it cannot be said that sufficient measures against the ultraviolet are achieved.

On the other hand, as a resin composition for cutting ultraviolet rays,
A resin composition is known in which 1 to 4 parts by weight of a benzotriazole compound and 0.5 to 8 parts by weight of an acrylic light diffusing agent are added to 100 parts by weight of a thermoplastic resin. 11-106666). Then, it is pointed out that it is also effective for cutting off the ultraviolet rays contained in the light of the fluorescent lamp, but it is premised on, for example, a molded body having a thickness of mm order. In other words, applications such as pipes and lighting covers that fit fluorescent lamps have been pointed out, but in thin applications, the amount of UV absorbers and light diffusers added increases, making it difficult to achieve the purpose. It is said that.

It is also known to form a translucent ultraviolet absorbing layer mainly composed of zinc oxide on the outer peripheral surface of the glass bulb in order to reduce ultraviolet radiation of the cold cathode fluorescent lamp (Japanese Patent Laid-Open No. 2001-2001). -126661). That is, the thickness of the resin containing an inorganic ultraviolet absorber such as zinc oxide or zinc oxide-titanium oxide is 0.1 to 3.0.
It has been pointed out that the ultraviolet radiation from the glass bulb can be suppressed by forming a layer of μm on the outer peripheral surface.
However, since the UV absorbing layer is a mixture / dispersion system of an organic resin and an inorganic powder, not only there is a problem of compatibility / uniformity, but also separation / detachment easily occurs in the long term. There's a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cold cathode fluorescent lamp and an illuminating device which can avoid damage and deterioration of peripheral members by absorbing and removing emitted ultraviolet rays.

[0012]

According to a first aspect of the present invention, there is provided a glass tube in which a phosphor film is formed on an inner wall surface and a rare gas and mercury are sealed therein, and a glass tube is disposed so as to face both ends of the glass tube. A cold cathode fluorescent lamp having a pair of cold electrodes, and one end connected to the cold electrode and the other end hermetically sealed and led out to the outside of the glass tube, the outer periphery of the glass tube. 1-thickness containing UV absorber over the entire length of the surface
The cold cathode fluorescent lamp is characterized in that a resin layer of 30 μm is provided.

According to a second aspect of the present invention, in the cold cathode fluorescent lamp according to the first aspect, the resin layer containing the ultraviolet absorber has an ultraviolet absorber content of 1 to 25% by mass.

The invention of claim 3 is the cold cathode fluorescent lamp according to claim 1 or 2, wherein the inner diameter of the glass arc tube is 6 mm or less.

According to a fourth aspect of the present invention, there is provided a lighting device having a lighting device having a connection terminal connected to a power supply lead wire of the fluorescent lamp, and a fluorescent lamp mounted on the lighting device. An illumination device comprising the cold cathode fluorescent lamp according to any one of claims 1 to 3.

In the invention of claims 1 to 3, the glass tube forming the arc tube generally has an outer diameter of 1.2 to 10.0 m.
m, preferably 2 to 6 mm, and a wall thickness of 0.2 to 0.
The glass tube has a length of about 6 mm and a length of about 50 to 800 mm. The phosphor film provided on the inner wall surface of the glass tube is usually formed of a phosphor used in this type of fluorescent lamp. Further, the discharge medium sealed in the glass tube is a mixed system of rare gas such as neon gas, argon gas, xenon gas or a mixed rare gas mainly composed of xenon gas and mercury. The amount of the discharge medium enclosed is the same as in the case of this type of cold cathode fluorescent lamp.

In the invention of claims 1 to 3, the polymer compound (organic resin) layer containing an ultraviolet absorber provided on the outer peripheral surface of the glass tube avoids or prevents ultraviolet rays from being emitted outside the glass tube. Therefore, it exhibits the function of absorbing and blocking ultraviolet rays. For example, it is a coating film in which a benzotriazole-based, benzophenone-based, or oxalic acid anilide-based UV absorber is contained and dispersed in an acrylic polymer at a mass ratio of about 1 to 25%.

Here, the content / dispersion amount of the ultraviolet absorber is 1
If it is less than mass%, the effect of absorbing and blocking ultraviolet rays will be insufficient, and if it exceeds 25 mass%, the mechanical strength or durability of the ultraviolet absorbent will decrease. The polymer compound used for forming the ultraviolet absorbing film may be an acrylic resin-based one, for example, a fluorine-based resin or a silicone-based resin, and is not particularly limited as long as it has physical properties capable of forming a light-transmitting film. Not done.

Further, it is desirable that the ultraviolet absorbing film on the outer peripheral surface of the glass tube extends (extends) outward from the region where the phosphor film is formed and extends over the entire outer peripheral surface of the glass tube. The thickness of the ultraviolet absorbing film on the outer peripheral surface of the glass tube is generally about 1 to 30 μm, preferably 5
It is about 20 μm. Here, if the thickness of the ultraviolet absorbing film is less than 1 μm, the effect of absorbing the ultraviolet rays is insufficient, and if it exceeds 30 μm, the translucency and durability may be impaired.

In the first to third aspects of the invention, the discharge electrode enclosed in the glass tube is, for example, Ni or Ni.
A cylindrical body or a columnar body having an outer diameter of about 0.6 to 2.0 mm and a length of about 2 to 5 mm made of a Ni-based metal such as an alloy, and the supply lead wires are connected by welding or the like. The discharge electrode may be configured to carry an electron emitting substance (emitter), and the sealing / arrangement in the glass tube is generally concentric with the glass tube.

In the invention of claim 4, the luminaire is not particularly limited as long as it is a general luminaire for a fluorescent lamp that performs a lighting operation using this type of fluorescent lamp as a light source.
Of course, the luminaire is selected according to the use and purpose.

According to the first to fourth aspects of the invention, the visible light transmitting organic ultraviolet absorbing film is provided on the outer peripheral surface of the glass tube. In other words, since the resin that functions as a binder or a forming film is added with an ultraviolet absorber that is also an organic material, it has a uniform durability due to the compatibility of the two and does not cause separation or the like. A layer having excellent properties is formed. Then, when a required high-frequency voltage is applied to the discharge electrode via the power supply lead wire, the ultraviolet light emitted along with the discharge between the discharge electrodes is converted into visible light by the phosphor film on the inner wall surface of the glass tube. However, the ultraviolet rays transmitted through the phosphor film and the glass tube wall are blocked or blocked from being radiated from the outer peripheral surface of the glass tube. Therefore, the irradiation of ultraviolet rays to the peripheral region is suppressed / prevented, and adverse effects such as deterioration of peripheral members due to ultraviolet rays are avoided / eliminated.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described below with reference to FIGS. 1, 2 and 3.

FIG. 1 is a cross-sectional view showing the structure of the essential parts of a cold cathode fluorescent lamp according to an embodiment. In FIG. 1, 12 is a hermetically sealed glass tube that functions as an arc tube, and 13 is a phosphor film provided on the inner wall surface of the glass tube 12. Here, the glass tube 12 has, for example, an outer diameter of 2 to 10 mm and a length of 50 to 750 mm, and is filled with a rare gas as a discharge medium, for example, a mixed system of rare gas mainly containing xenon gas and mercury. . In this embodiment, the glass tube has an outer diameter of 2.6 mm and an inner diameter of 2.0 mm, which is almost a perfect circle and has a total length of 22.
1 mm, the distance between the electrodes is 211 mm, the discharge medium is a mixed rare gas of neon and argon, and mercury.

Further, 14a and 14b are the glass tubes 5 described above.
A pair of discharge electrodes sealed at both ends inside, 15a, 15b
Is a supply lead wire having one end connected to the discharge electrodes 14a, 14b and the other end being hermetically sealed and led out of the glass tube 12, and 16 is a visible light transmission provided on the outer peripheral surface of the glass tube 12. It is a polymer (organic resin) film that absorbs ultraviolet rays. Here, the discharge electrodes 14a and 14b are made of, for example, Ni.
The inner diameter of the opening at one end of the system is about 2.0 mm, and the length is 4.0 m
It is a cylindrical body of about m and provided with an electron emissive material film on its inner and outer wall surfaces. In addition, the supply lead wires 15a, 15
b is, for example, a tungsten wire, a nickel wire, an iron wire, a molybdenum wire having a diameter of about 0.3 to 1.0 mm, or a composite metal wire thereof, one end of which is connected to the bottom wall surface of the cylindrical body by welding means.

Further, the ultraviolet absorbing film (resin layer or polymer film in which the ultraviolet absorbent is dispersedly contained) 16 is made of, for example, an acrylic polymer in which 5% by mass of a benzotriazole ultraviolet absorbent is contained and dispersed. It is a coating film. Specifically, in the acrylic polymer system containing and dispersed the ultraviolet absorber, the cold cathode fluorescent lamp having the above configuration is immersed,
A thickness formed by pulling the lamp in the axial direction at a constant speed, drying and baking at a temperature of 190 ° C. for 10 minutes,
It is a uniform coating film of about 5 μm.

In the cold cathode fluorescent lamp, a high frequency voltage (for example, 20 to 100 KHz, 1 to 4 K) required for the discharge electrodes 14a and 14b via the supply lead wires 15a and 15b.
When a voltage of V is applied), discharge starts between the discharge electrodes 14a and 14b, and ultraviolet rays are emitted into the glass tube 12. The ultraviolet rays thus radiated are converted into visible light by the phosphor film 13 on the inner wall surface of the glass tube 12, and the visible light is transmitted and radiated to the outside of the glass tube 12.

In this lighting operation, in the cold cathode fluorescent lamp, the polymer 16 that transmits visible light and absorbs ultraviolet rays is uniformly provided on the outer peripheral surface of the glass tube 12, so that ultraviolet rays are emitted to the outside of the glass tube 12. Suppress and prevent radiation. That is, since the emission of ultraviolet rays to the periphery of the glass tube 12 is prevented / suppressed, the inconvenience caused in the peripheral portion by the emission of ultraviolet rays is eliminated. FIG. 2 shows the spectral characteristics of the emitted light of the cold cathode fluorescent lamp due to the lighting operation.
Exhibits higher radiant intensity in the 0-620 nm region and has a wavelength of 4
Ultraviolet radiation below 00 nm is prevented. It was confirmed that no peeling or damage of the ultraviolet absorbing film was observed during the above-mentioned lighting operation, and the durability was excellent.

Further, with the cold cathode fluorescent lamp having the above-mentioned structure incorporated in a back lighting device, it is attached to a corresponding inverter lighting circuit: HIU-742A, and a lighting frequency of 42 is set.
The lamp was lit under the conditions of KHz, lamp current 7 mA, and ambient temperature 25 ° C., and the relationship between the lighting elapsed time and the plate surface luminance maintenance rate (%), that is, the continuous lighting life test was performed, and FIG.
It was confirmed that the decrease in the brightness of the panel surface was suppressed and prevented, and a good continuous lighting life was exhibited, as shown in. On the other hand, for comparison, a back lighting device incorporating a cold cathode fluorescent lamp having the same configuration and standard as described above, except that the ultraviolet absorbing polymer film 16 is not formed by coating on the outer peripheral surface of the glass tube 12,
When the continuous lighting life test was performed under the same conditions, the tendency shown by the curve a in FIG. 3 was confirmed. In addition, each continuous lighting life test is an average value for five back lighting devices.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the composition and thickness of the ultraviolet absorbing polymer film that transmits visible light but absorbs and blocks ultraviolet light, the dimensions of the fluorescent lamp, and the like can be appropriately selected according to the application.

[0031]

According to the first to third aspects of the present invention, since the ultraviolet radiation from the outer peripheral surface of the glass tube is blocked / blocked at the time of driving the lighting, deterioration of the peripheral members due to the ultraviolet radiation is also eliminated.

According to the fourth aspect of the present invention, the adverse effects of ultraviolet radiation from the lamp, such as the deterioration of the components of the peripheral portion of the back lighting device due to ultraviolet rays, are eliminated, so that the lighting device contributes to the improvement of reliability and durability. Will be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a cold cathode fluorescent lamp according to an embodiment.

FIG. 2 is a curve diagram showing a spectral distribution characteristic of a cold cathode fluorescent lamp according to an example.

FIG. 3 is a characteristic diagram showing a continuous plate surface luminance maintenance ratio in a state where the cold cathode fluorescent lamp according to the example is incorporated in a back lighting device, as compared with the case of a conventional cold cathode fluorescent lamp.

FIG. 4 is a sectional view showing a schematic configuration of a conventional cold cathode fluorescent lamp.

FIG. 5 is a curve diagram showing a spectral distribution characteristic of a conventional cold cathode fluorescent lamp.

FIG. 6 shows a configuration example of a backlight unit,
(A) is a development view, (b) is an assembly configuration diagram.

[Explanation of symbols]

1,13 ... Phosphor film 2,12 …… Glass tube 3a, 3b, 14a, 14b ... Discharge electrodes 4a, 4b, 15a, 15b ... Supply lead wire 16 ... UV absorbing polymer film

Claims (4)

[Claims] 1. A glass tube having a phosphor film formed on its inner wall surface and containing a rare gas and mercury sealed therein, a pair of cold electrodes sealed so as to face both ends of the glass tube, and the cold electrode. A cold cathode fluorescent lamp having a lead wire for power supply, one end of which is connected to the glass tube and the other end of which is hermetically sealed and led out of the glass tube, wherein the thickness is 1 to 30 μm over the entire outer peripheral surface of the glass tube.
A cold cathode fluorescent lamp, wherein a resin layer containing the organic ultraviolet absorber according to 1) is provided. 2. The cold cathode fluorescent lamp according to claim 1, wherein the resin layer containing the organic ultraviolet absorber has an organic ultraviolet absorber content of 1 to 25% by mass. 3. The cold cathode fluorescent lamp according to claim 1, wherein the glass tube has an inner diameter of 6 mm or less. 4. A lighting device comprising: a lighting device having a connection terminal connected to a power supply lead wire of the fluorescent lamp; and a fluorescent lamp mounted on the lighting device, wherein the fluorescent lamp is a fluorescent lamp. 3. A lighting device, which is the cold cathode fluorescent lamp according to any one of 3).